Truing and feeding method and apparatus for grinding machines



Nov. 3, 1964 C. l. CRNEHAGE TRUING AND FEEDING METHOD AND APPARATUS FOR GRINDING MACHINES Filed March 5, 1963 FIGI.

INVENTORI BY CURT INGE ORNEHAGE ATTYS United States Patent Q 3,155,986 TRUlNG AND FEEDING METHOD AND APPA- RATUS FOR GRENDING MACHINES Curt Inge Ornehage, Lidiroping, Sweden, assignor to Lidkopings Mekanisha Verkstads Ahtiebolag, Lidkoping, Sweden, a corporation of Sweden Filed Mar. 5, 1963, Ser. No. 262,979 Claims priority, application Sweden Mar. 10, W62 11 Claims. (Cl. 125-11) The present invention relates to a new and improved method and apparatus for truing a grinding wheel of a grinding machine, such as a centerless grinder.

In centerlcss grinding machines the work piece is disposed between the grinding wheel and a support member and feed means is provided to cause relative movement of the grinding wheel and the support member. In the grinding machine illustrated, the support member is fixed and the grinding wheel is movable. During operation of the grinder, it is usually necessmy to true the grinding wheel after a predetermined number of feeding advances of the grinding wheel or after a certain number of work pieces have been ground on the machine. Truing of the grinding wheel is usually done by means of a truing tool movable relative to the grinding wheel between a rest limit position at one side of the grinding surface of the grinding wheel and a reversing limit position at the opposite side of the grinding surface and operable to engage the grinding surface during movement between limit positions to true the grinding surface. grinding wheel is trued, the grinding wheel should be located so that the first work piece which is ground after the truing operation will be ground to a size falling within specified tolerance limits so that when grinding Work pieces in series, all of the finished work pieces are ground to a size falling within specified tolerance limits.

In accordance with the present invention, this is accomplished by providing a control member having a circumferential control surface adapted to be engaged by the truing device during movement thereof between limit positions and sensing means cooperable with the control surface and the grinding wheel feed means to sense changes in the diameter of the control surface effected by the truing device and to actuate the feed means to cause a predetermined relative movement of the grinding wheel and support member. By this arrangement, changes in the diameter of the grinding wheel effected by the truing operation are compensated for and accordingly, each of a series of work pieces ground on the machine falls within specified tolerance limits.

The truing device rough trues the grinding wheel during movement from its rest to its reversing position and finish trues the grinding wheel on its return stroke from the reversing to the rest position. In the embodiment of the invention illustrated, the control member is disposed at the side of the grinding surface adjacent the reversing position and the sensing means is conditioned to sense and actuate prior to the truing device returning to its rest position whereby adjustment of the grinding wheel is effected quickly and there is a minimum delay in operation of the grinding machine due to truing.

With the foregoing in mind, an object of the present invention is to provide a novel method and apparatus for truing and adjusting grinding machines whereby each of a series of work pieces is finished to specified tolerance limits.

Another object of the present invention is to provide a novel truing and feeding method for grinding machines and apparatus for carrying out the method which is of comparatively simplified construction whereby the grinding machine may be manufactured economically.

A further object of the present invention is to provide After the a novel truing and feeding method and apparatus for grinding machines whereby truing of the grinding wheel and adjustment thereof to compensate for changes therein effected by truing may be accomplished quickly thereby minimizing delay in the operation of the grinding machine.

These and other objects of the present invention and the various features and details of the operation and construction thereof are hereinafter more fully set forth with reference to the accompanying drawing, in which:

FIG. 1 is a side view of a portion of a grinding machine embodying the present invention; 7

FIG. 2 is a plan view of a portion of the grinding machine shown in FIG. 1; and

FIG. 3 is a thumb nail view of a grinding wheel wherein the control member is formed integrally with the grinding wheel.

Referring now to the drawing, there is shown in FIGS. 1 and 2 a centerless grinding machine embodying the present invention. The grinding machine comprises a grinding wheel 1 supported on a shaft 1a rotatably mounted in a carriage 2 which is displaceable along guides [not shown] relative to the base 3 in the directions indicated by the arrow A. A work piece 4 is supported on a support plate 5 between the grinding wheel 1 and a support wheel 6.

The grinding wheel 1 is trued by a truing device movable between a rest limit position at one side of the grinding surface 1b of the grinding wheel (see FIG. 2) and a reversing limit position at the opposite side of the grinding surface 115. The truing device comprises a diamond 9 mounted in a holder 8 which in turn is held in a support 7. The support 7 is movable in a direction substantially parallel with the axis of the grinding wheel 1 along a guide it The holder 8 which can be displaced relative to the support 7 in the direction indicated by the arrow B and is provided with a contact finger 11 which is held in engagement with the profiled edge of a templet 12 by means of a spring 20 and thus, follows the contour of the templet during movement of the support along the guide 10 whereby the grinding wheel 1 will be shaped to the profile determined by the templet 12 during actuation of the truing device between limit positions. During the truing operation, the truing device moves in the direction indicated by the arrow C from the rest limit position to a reversing limit position at the opposite side of the grinding wheel, the diamond 9 being set to contact the grinding surface 1b of the grinding wheel to provide a rough truing cut. The diamond 9 is then advanced slightly in the holder 8 toward the grinding surface 1b and the truing device is then returned to the rest limit position to finish true the grinding surface 112.

In accordance with the present invention means is provided for sensing changes in diameter of the grinding surface of the grinding wheel effected by truing and for effecting a predetermined relative movement of the grinding wheel and support wheel to compensate for changes resulting from truing whereby each of a series of work pieces is ground to specified tolerance limits. To this end, there is provided a control member, in the present instance, in the form of a disk 13 having a circumferential control surface 15 concentric with the grinding surface lb, the disk 13 mounted on the shaft 1a at the side of the grinding surface adjacent the reversing position of the truing device in the path of movement thereof. Further, sensing means is provided comprising, in the present instance, a pneumatic gauge 14 which is mounted on the frame 13 and which cooperates with the control surface 15 to sense changes in the diameter of the control surface 15 effected by the truing device. The gauge 14 includes a nozzle 16 which may be connected to a suitable fluid source under pressure and which confronts the control surface 15 and is normally spaced a predetermined distance D therefrom to provide a predetermined back pressure at the nozzle 16. In the present instance, the nozzle 16 is located substantially in a plane common to the axes of the grinding wheel 1, the control disk 13 and the Work piece 4. The gauge 14 is connected to an operator 1% and a suitable electrical power source through leads 19, the operator 18 being adapted to actuate the feed means for the grinding wheel in response to corrective signals from the gauge 14. In the present instance the operator 18 is conditioned to actuate the feed means when the truing device engages the control surface 15 and accordingly a normally open micro-switch 2h connected to the operator 18 through electrical leads 21 is mounted at one end of the slide and which is adapted to be closed by the truing device to condition the operator when the truing diamond 9 traverses the control surface 15.

In the present instance, the diameter of the control disk 13 .is smaller than that of the grinding wheel 1 and control disk 13 is made of a material less porous than that of the grinding wheel, e.g. Bakelite or similar plastic material. Even though the control disk 13 is shown as a separate member, an alternate arrangement is that shown in FIG. 3 wherein the control disk 13 is formed integrally with the grinding wheel 1'. It is noted that in this arrangement the control disk portion is of a finer structure.

Considering now the operation of the grinding machine, during normal operation the truing device is disposed in the rest limit position and the nozzle 1c is located a predetermined distance D from the control surface 15 to provide a predetermined back pressure at the nozzle 16, at which pressure no corrective signal is transmitted from the gauge 14 to the operator 18. It is noted that under these conditions, the micro-switch 2G is open. After a certain number of forward feeding operations of the grinding wheel 1 towards the work piece depending on the wear on the grinding wheel or alternatively after a certain number of work pieces have been ground, the grinding wheel 1 is trued by advancing the diamond 9 from the rest position shown in FIG. 2 and permitting it to traverse the grinding wheel and thereafter the control disk 13. During this movement of the truing device, the diameter of the grinding wheel 1 and control disk 13 are reduced. Accordingly the distance between the nozzle 16 and the control surface 15 is greater than the predetermined distance D whereby the back pressure at the nozzle 16 drops and the gauge 14 signals the operator 18 to actuate the feed means to advance the grinding wheel, the operator 18 having been conditioned by closing of the micro-switch 20 by the tru-ing device as it traversed the control surface 15. The grinding wheel 1 is advanced until the distance between the nozzle 16 and the control surface 15 corresponds to the predetermined distance D whereby the corrective signal from gauge 14 to the operator is cut off. When the diamond 9 has reached the reversing limit position, it is advanced slightly towards the grinding surface 1b and then the truing device is returned to the rest position during which stroke, finish truing of the control surface and the grinding surface 1b takes place. During this finish truing operation, however, the diameter of the grinding wheel 1 and the control disk 13 have been somewhat reduced and the distance between the nozzle '16 and the control surface 15 increased. Accordingly the gauge 14 signals the operator 18 to advance the grinding wheel until the gauging pressure of the pneumatic gauge 14- attains a predetermined value when further advance is automatically discontinued. It is noted that the micro-switch 20 remains closed until the truing diamond 9 has traversed the control surface. The position of the grinding wheel 1 is then such that the dimensions of the first work piece to be ground after the truing operation will lie. within the prescribed tolerance limits. Since the control disk 13 is adjusted in the same operation as'the grinding wheel, each position of the same relative to the gauging device will always correspond to a certain position of the working surface of the grinding wheel.

In accordance with the above described arrangement, the time required for the truing and the grinding wheel adiustment is maintained at a minimum. For example, considering briefly a complete cycle of operation, the diamond 9 starts from its rest position (see FIG. 2) and moves to its reversing position. During the course of this movement, the diamond has trucd both grinding wheel 1 and the control disk 13 from one direction. When the diamond 9 reaches this position, the slide 2 is automatically advanced to compensate for the decrease .in diameter of the grinding wheel 1. After forward adjustment of the diamond 9, its movement is reversed, and it first passes the control disk 13 and then the grinding wheel 1. Since during this return movement the control disk 13 is first adjusted to finish diameter, the grinding wheel 1 can be advanced to correct position at the same time as it is being trued. In this manner the time required for the advancing operation itself is saved since it takes place simultaneously with the finish truing of the grinding wheel. When the grinding wheel is in grinding position and the truing device has returned to rest position, the grinding operation is resumed.

The device described above thus eliminates all inaccuracies which would otherwise be caused by advancing the diamond or may be due to wear on the same or change of its position such as may occur if it is turned in its holder, for which reason, dimensions of the first work piece to be ground after the truing operation can be made to fall within a very limited tolerance zone.

While a particular embodiment of the present invention has been described herein, it is to be understood that changes and modifications may be incorporated therein within the scope of the following claims.

1 claim:

1. In a grinding machine including a rotatably mounted grinding wheel having a grinding surface, a support member, a truing device movable between a rest limit position at one side of the grinding surface and a reversing limit position at the opposite side of the grinding surface, said truing device adapted to engage said grinding surface during actuation between limit positions to true the grinding surface and feed means for effecting relative movement of the grinding wheel and support member; a control member having a circumferential control surface adapted to be engaged by the truing device during movement thereof between limit positions, sensing means cooperable with said control surface and the feed means to sense the changes in the diameter of said control surface effected by the t-ruing device and to actuate the feed means to cause a predetermined relative movement of the grinding wheel and support member thereby to compensate for the changes eifected by the truing device.

2. A grinding machine as claimed in claim 1, wherein said control member is formed integrally with the grinding wheel.

3. A grinding machine as claimed in claim 1, where in said control member is a disk made of a material of less porosity than the material of the grinding wheel.

4. A grinding machine as claimed in claim. 1, wherein the control member is disposed to one side of the grinding wheel adjacent the reversing limit position of the truing device.

5. A grinding machine as claimed in claim 1, including means for conditioning said sensing means to sense and actuate after the truing device has traversed the control surface.

6. A grinding machine as claimed in claim 1, including means for conditioning said sensing means to sense and to actuate during movement of the truing device from the reversing to the rest position whereby feeding iovement is completed before truing device reaches its rest position.

7. in a grinding macm cluding a ro-tatably mounted grinding wheel having a grinding surface, a support member, a truing device movable between a rest limit position at one side of the grinding surface and a reversing limit position at the opposite side of the grinding surface, said truing device adapted to engage said grinding surface during actuation between limit positions to true the grinding surface and feed means for eifecting relative movement of the grinding wheel and support member; a control member having a circmnferential control surfac adapted to be engaged by the truing device during movement thereof between limit positions, a sensing gauge ha *ing a nozzle confronting said control surface and spaced therefrom a predetermined distance, said sensing gauge cooperable with said feed means to sense changes in the distance betwee said nozzle and the control surface from said pre etcmiined distance effected by said truing device and to actuate the feed means to cause a predetermined relative movement of the grinding Wheel and support member thereby to compensate for changes effected by the truing device.

8. A grinding machine as claimed in claim 7 wherein said control member is a disk and wherein the smallest radius of the grinding wheel is greater than the combination of the radius of the control disk and said predetermined distance between said nozzle and said control surface.

9. A method for truing a grinding Wheel of a grinding machine including a support member, feed means for moving the grinding wheel relative to the support and a truing device movable between a rest limit position at one side of the grinding surface and a reversing limit position at the opposite side thereof, consisting of the steps of providing a cylindrical control surface at the opposite side of the grinding surface, moving the turning device between a. rest position at one side of the grinding surface and a reversing position at the other side of the grinding surface to engage the grin 'ng wheel to true same and also the control surface thereby to efl'ect a change in the diameter of the control surface, sensing the change in the diameter of the control surface and effecting a predetermined relative movement of the grinding wheel and support member in response to changes in the diameter of the control surface thereby to compensate for changes effected by the truing device.

10. A method as claimed in claim 9, wherein adjusting movement of the grinding Wheel is etfected after movement of the itruing device from its rest to its reversing limit positions.

11. A method as claimed in claim 9, wherein adjusting movement of the grinding Wheel is effected after movemerit of the truing device has reached its reversing limit position.

References (Iited in the file of this patent UNITED STATES PATENTS 

1. IN A GRINDING MACHINE INCLUDING A ROTATABLY MOUNTED GRINDING WHEEL HAVING A GRINDING SURFACE, A SUPPORT MEMBER, A TRUING DEVICE MOVABLE BETWEEN A REST LIMIT POSITION AT ONE SIDE OF THE GRINDING SURFACE AND A REVERSING LIMIT POSITION AT THE OPPOSITE SIDE OF THE GRINDING SURFACE, SAID TRUING DEVICE ADAPTED TO ENGAGE SAID GRINDING SURFACE DURING ACTUATION BETWEEN LIMIT POSITIONS TO TRUE THE GRINDING SURFACE AND FEED MEANS FOR EFFECTING RELATIVE MOVEMENT OF THE GRINDING WHEEL AND SUPPORT MEMBER; A CONTROL MEMBER HAVING A CIRCUMFERENTIAL CONTROL SURFACE ADAPTED TO BE ENGAGED BY THE TRUING DEVICE DURING MOVEMENT THEREOF BETWEEN LIMIT POSITIONS, SENSING MEANS COOPERABLE WITH SAID CONTROL SURFACE AND THE FEED MEANS TO SENSE THE CHANGES IN THE DIAMETER OF SAID CONTROL SURFACE EFFECTED BY THE TRUING DEVICE AND TO ACTUATE THE FEED MEANS TO CAUSE A PREDETERMINED RELATIVE MOVEMENT OF THE GRINDING WHEEL AND SUPPORT MEMBER THEREBY TO COMPENSATE FOR THE CHANGES EFFECTED BY THE TRUING DEVICE. 